III. THE OXIDATION OF TYRAMINE BY RAT LIVER HOMOGENATES

Abstract

The oxidation of tyramine by rat liver homogenates in vitro is stimulated by cytochrome C, coenzyme I, α-keto acids, methylene blue, and aluminum and calcium ions. A possible mechanism of reaction involving a coupled reaction between a dehydrogenase ("amine oxidase") with tyramine as substrate and the lactic dehydrogenase in the presence of pyruvate, the cytochrome-cytochrome oxidase system serving as final path to oxygen, is described. This reaction is followed by oxidation of the p-hydroxyphenylacetaldehyde to p-hydroxyphenylacetic acid, possibly catalyzed by xanthine-aldehyde oxidase, Oxidation of the ring of tyramine also is suggested.